In the related art, there is known a method of forming a silicon nitride film on a semiconductor wafer by using an ALD (Atomic Layer Deposition) method in which an adsorption step and a nitriding step are repeated.
In the case of forming a silicon nitride film on a semiconductor wafer by using an ALD method, the film formation time is shortened and the productivity is improved, for example, by a method of increasing a process temperature to enhance the adsorption efficiency of a raw material gas or a method of shortening the time of one cycle.
However, in the method of increasing the process temperature, uniformity may deteriorate due to a CVD reaction. In the method of shortening the time of one cycle, the reaction time per cycle is shortened. Therefore, the adsorption reaction and the nitriding reaction may become insufficient and the film quality may deteriorate. Thus, in the method of related art, it was difficult to achieve both the enhancement in productivity and the improvement in film quality.